Andreas Hvid posted a video apparently of himself and a model climbing the pyramid at night.

Egyptian authorities are reportedly investigating after a Danish photographer posted a photograph of himself and a woman in a sexual pose apparently on top of the Great Pyramid of Giza.

Andreas Hvid also posted a video apparently showing the two of them climbing the pyramid at night, with the woman taking her top off at the summit, revealing her bra, with the skyline of Cairo in the background. The woman’s face was pixellated.

The footage and image triggered fury in Egypt and on social media, with many arguing it was disrespectful to the nation’s heritage.

One angry Twitter user wrote: “ewww at this denmark guy claiming to be photographer but cant be bothered to abide simple rules. The disrespect by climbing over protected monument like pyramids like ewww what disgusting behaviour from people claiming to be from 1st nation country yucks.”

Prosecutors in the strictly conservative Muslim country will investigate whether the video is real after officials suggested it might be fake, according to Egyptian media reports.

They will also look into how the couple climbed the 140-metre (460ft) pyramid, which is one of the seven wonders of the world.

On Saturday, the Egyptian antiquities minister, Khaled al-Anani, said scaling the pyramids was “strictly forbidden” and branded the images a “violation of public morality”, according to the newspaper al-Ahram.

The pair claim to have entered the historic site late November. Hvid told the Danish tabloid Ekstrabladet that he had contacted women in Denmark to complete the picture with him. “Luckily one … had the opportunity to come to Cairo at short notice,” he said.

The two waited until the area around the pyramid had become less busy, and then made the climb, which took about 25 minutes, he said. “A euphoric feeling struck us both when we reached the top,” he told the paper. “It was the culmination of a lot of work and many chances taken.”

He denies having sex on the pyramid. “We did not have sex and we never had it.”

The photographer regularly posts images of sexual scenes involving nudity against breathtaking skylines on his Instagram page. Naked women scaling city cranes or resting among woodland ruins are among photographs in his collection.